In addition to the FAQ below, see also the EMF Model Query Developer Guide documentation included in the EMF Query SDK.
Newbie / General
Does EMF Query 1.1 work with J2SE 1.4?
Mostly, yes. The core EMF Query framework works with EMF 2.2 or higher and J2SE 1.4.
However, the OCL extensions in the org.eclipse.emf.query.ocl plug-in require OCL 1.1 and EMF 2.3. Consequently, using OCL with EMF Query requires J2SE 5.0 or greater. See also EMF 2.3 JVM Requirements.